At present, the miniaturization of electric elements has been advanced, and as a result, the miniaturization of individual elements has been approaching the limitation thereof. In the case of, for example, CMOSes, which are current leading memory elements, it is expected that the minimum value of their channel length permitting their functions to be expressed would be 6 nm. In order to develop new techniques exceeding this limit, the development of new elements has been advanced on the basis of various ideas throughout the world.
For example, about memory elements, two-terminal resistance switching elements have been researched, in which a large change in resistance is generated between on-states and off-states of the elements through the migration of atoms or a change in property of molecules. Typical examples thereof will be introduced hereinafter.
A technique introduced in Nature 433, (2005) 47-50 is a technique of using an electrochemical reaction between a silver sulfide electrode and a platinum electrode to stretch and shrink silver particles to control, through the silver atoms, the bridging and breaking between the electrodes, thereby realizing an atomic switch.
A technique introduced in SCIENCE 289, (2000) 1172-1175 is a technique of using a redox reaction of catenane-type molecules and inducing the redox reaction of the molecules by a voltage, so as to open a channel, thereby realizing a switching element.
As described above, in recent years, reports have been made on switching elements using the stretching and shrinking of a small number of metal atoms or a redox reaction of molecules.
As illustrated in FIG. 7, the inventors of the present invention proposed a two-terminal resistance switching element in which a voltage is applied to metallic electrodes with a nanogap width across the electrodes (Nanotechnology 17, (2006) 5669-5674). The technique introduced in this literature is a technique of applying a voltage to gold electrodes with a gap width of about 10 nm across the electrodes so as to control the gap width. It is demonstrated that, according to this technique, the resistance value of the gap portion can be controlled and the element can be applied as a non-volatile memory, using the control of the gap width. A resistance change model diagram of a resistance switching phenomenon of the nanogap electrodes is shown in FIG. 2.
However, since metal is used for the electrodes which constitute the element, the technique for working the electrodes is restricted, and further electric characteristics of the electrodes themselves, and others have not been easily controlled.